Table of Content

10 June 2025, Volume 44 Issue 5

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Carbon storage and influencing factors of typical forest ecosystems in loess hilly region.

YE Xiaoman, WEI Tianxing, YU Huan, ZHANG Xiaoming, FAN Dehui, JIANG Shan, XIN Pengcheng, LI Shijie

2025, 44(5):  1409-1416.  doi:10.13292/j.1000-4890.202505.025

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Analyzing the carbon storage distribution pattern and its influencing factors of typical forest ecosystems in loess hilly region can provide support for the evaluation of forest carbon pool on the Loess Plateau. In this study, Pinus tabuliformis forest, Robinia pseudoacacia forest, Platycladus orientalis forest, Pinus tabuliformis+Robinia pseudoacacia mixed forest, and Platycladus orientalis+Robinia pseudoacacia mixed forest were selected as research objects in loess hilly region. The distribution characteristics and influencing factors of carbon storage in vegetation layer (tree, shrub, grass, and litter) and 0-100 cm soil layer of typical forest ecosystems in loess hilly region were analyzed by plot investigation method combined with principal component analysis and random forest model. The results showed that: (1) Ecosystem carbon storage was in order of Pinus tabuliformis+Robinia pseudoacacia mixed forest > Platycladus orientalis+Robinia pseudoacacia mixed forest > Pinus tabuliformis forest > Robinia pseudoacacia forest > Platycladus orientalis forest. Vegetation carbon storage of the Pinus tabuliformis+Robinia pseudoacacia mixed forest was the largest, while the Robinia pseudoacacia forest the smallest. Soil carbon storage was the highest in the Platycladus orientalis+Robinia pseudoacacia mixed forest and the lowest in the Platycladus orientalis forest. (2) There was a positive relationship of carbon storage between vegetation and soil, accounting for 15.72%-34.86% and 65.14%-84.28% of total ecosystem carbon storage, respectively. Soil carbon storage was the main body of ecosystem carbon storage. The ratio of underground and aboveground carbon storage varied from 1.87 to 5.36, and the vegetation layer still had strong carbon sequestration potential. (3) Soil total nitrogen, total phosphorus, available phosphorus, soil available potassium, soil clay, and plant diversity explained 84.14% and 95.88% of variation of carbon storage in vegetation layer and soil layer, respectively. Among them, biomass (26.25%) had the greatest contribution to the variation of carbon storage in vegetation layer. Total nitrogen (19.01%), total phosphorus (18.41%) and available potassium (15.28%) were the main factors affecting the vertical distribution of soil carbon storage. The carbon storage of forest ecosystems in loess hilly region was affected by community characteristics and soil physical and chemical properties. Under the similar stand age, carbon storage of mixed forest was higher than that of pure forest. Coniferous and broad-leaved mixed forest can be preferred when planting artificial forest on the Loess Plateau.





Relationship between spatial structure and hydrological effect of Pinus tabuliformis plantation in the loess region of western Shanxi Province.

TANG Peng, ZHANG Jianjun, ZHAO Jiongchang, HU Yawei, LI Yang, WANG Siqi, WEI Zhaoyang

2025, 44(5):  1417-1426.  doi:10.13292/j.1000-4890.202505.019

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Understanding the relationships between spatial structure of forest stand and the hydrological effects of canopy, litter and soil layers is important for the sustainable management and water conservation functioning of plantations. In this study, we analyzed the relationships between spatial structure parameters (angle scale, size ratio, openness, competition index, and canopy layer index) and the hydrological effects of canopy, litter and soil layers in Pinus tabuliformis plantations with six stand densities (1000, 1800, 2700, 3600, 4400, and 5200 trees·hm^-2) in Caijiachuan watershed in Jixian County, Shanxi Province. The results showed that Pinus tabuliformis plantation with a density of 1000 trees·hm^-2 exhibited the most optimal spatial structure, characterized by weaker competition among trees, higher openness, and a more complex canopy structure with a higher proportion of dominant trees. With increasing stand density, spatial structure deteriorated. At the density of 1000 trees·hm^-2, the maximum canopy interception was 7.30 t·hm^-2. At the density of 2700 trees·hm^-2, litter accumulation, the maximum litter water-holding capacity, and the maximum soil water-holding capacity (0-100 cm) were the highest, at 26.69 t·hm^-2, 4.11 mm, and 52.33 mm, respectively. Therefore, regulating stand density to 2700 trees·hm^-2 maximized the overall hydrological effect evaluation index for the canopy, litter, and soil layers. The size ratio was significantly negatively correlated with litter accumulation, maximum litter water-holding capacity, maximum soil water-holding capacity, and capillary water-holding capacity (P<0.05). Soil non-capillary water-holding capacity was significantly positively correlated with openness (P<0.05) and negatively correlated with competition index (P<0.05). The size ratio, canopy layer index, and openness were key spatial structure parameters affecting the hydrological effects of Pinus tabuliformis plantation.





Effects of stand densities on growth characteristics of Pinus tabuliformis plantation in loess region of western Shanxi Province.

YANG Zhou, ZHANG Jianjun, ZHAO Jiongchang, HU Yawei, LI Yang, TANG Peng, WANG Bo

2025, 44(5):  1427-1435.  doi:10.13292/j.1000-4890.202505.021

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Investigating the growth, biomass, and biomass allocation characteristics of forest plantations under different stand densities offers theoretical support for the sustainable management and high-quality development of plantations. We conducted field surveys and stem analysis of sample trees to explore the differences in growth process, biomass, and biomass allocation of 50-year-old Pinus tabuliformis plantations with stand densities of 600, 930, 1200, and 1650 trees·hm^-2. The results showed that: (1) The rapid growth period of the diameter at breast height (DBH) of Pinus tabuliformis was between 5 and 20 years old, and then entered a slow growth phase. Tree height had a rapid growth phase between 5 and 15 years old, followed by a slow growth stage. The ages at which DBH and tree height entered the slow growth phase varied among different stand densities. The lowest density (600 trees·hm^-2) delayed such transition, while the highest density (1650 trees·hm^-2) entered the slow growth phase earliest. The basal area growth remained fast before the age of 40 years, and continued to grow rapidly at 50 years for the density of 930 trees·hm^-2. (2) Aboveground biomass did not enter a slow growth phase at the age of 50. The growth was fastest at 930 trees·hm^-2 and slowest at 1650 trees·hm^-2 at the age of 50. (3) Aboveground biomass of individual trees ranged from 55.78 to 105.21 kg and decreased with increasing stand density. Across all stand densities, biomass allocation in various organs was in order of trunk > branch > needle. For cultivating large-diameter timber, the density of 600 trees·hm^-2 is recommended. The density should be adjusted at the age of 20 years. For carbon sequestration and ecological functions in water and soil conservation forests, biomass accumulation should be prioritized. In this situation, stand density should be adjusted to 930 trees·hm^-2 at around 40 years based on the basal area. In the actual tending and management of Pinus tabuliformis plantations, appropriate density regulation measures should be selected according to different silvicultural requirements.





Variations in bark thickness of common tree species in the karst seasonal rainforest of Nonggang and their environmental explanations.

WANG Yanping, WANG Bin, LU Fang, TAO Wanglan, LI Jianxing, HUANG Fuzhao, GUO Yili, XIANG Wusheng, LI Xiankun

2025, 44(5):  1436-1447.  doi:10.13292/j.1000-4890.202505.020

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Bark is composed of all tissues outside vascular cambium, the functional characteristics of which reflect important ecological adaptation strategies of plants. To reveal the differences in bark thickness of common tree species in the karst seasonal rainforest among different taxonomic groups and functional groups, as well as the impacts of biological and environmental factors, 128 common tree species with an abundance greater than 20 in a 15 hm² permanent monitoring plot of Nonggang were analyzed. The differences in bark thickness between different taxa and functional groups, as well as the impacts of biological and environmental factors on bark thickness were quantified. The results showed that the average total bark thickness, outer bark thickness, and inner bark thickness of the 128 tree species were 2.95, 0.70, and 2.26 mm, respectively. The bark of trees from Linaceae, Bignoniaceae, and Icacinaceae families was relatively thicker. The thickness of bark showed significant differences among different taxa and functional groups, with inner bark thickness > outer bark thickness. Among different functional groups, bark thickness was in order of: deciduous species > evergreen species (excluding outer bark thickness), and tree species > small tree species > shrub species. The phylogenetic signal for bark thickness was relatively weak, so bark thickness was primarily influenced by habitat factors. Among various biological factors affecting bark thickness, species identity had the highest explanatory power. Additionally, bark thickness variation was driven by topographical and soil factors, with similar patterns across different locations. Total bark thickness correlated with stand factors and environmental factors. In summary, bark thickness of tree species in the karst seasonal rainforest community in Nonggang is relatively thin, with significant variation among different tree species and functional groups. This indicates the adaptability of these tree species to the local humid climate. The explanation of bark thickness by environmental factors reveals the strategies employed by tree species to adapt to different environmental conditions and ecological niches by adjusting their bark thickness.





Leaf anatomical structure of Populus euphratica at different age classes and its correlation with salt resistance.

SONG Shuangfei, WANG Jie, HUANG Wenjuan, JIAO Peipei, YAO Shiyu, PENG Chengzhi, ZHANG Hailong

2025, 44(5):  1448-1455.  doi:10.13292/j.1000-4890.202505.023

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Leaf anatomical structure of Populus euphratica naturally distributed in Shaya County, Xinjiang at five different developmental stages was examined using conventional paraffin section method. We measured leaf thickness, upper and lower cuticle thickness, upper and lower epidermis thickness, spongy tissue thickness, palisade tissue thickness, and the ratio of palisade tissue to spongy tissue. Combining the methods of coefficient of variation and principal component analysis, four important indicators related to salt tolerance, namely leaf thickness, spongy tissue, palisade tissue, and midvein vascular bundle area, were identified. The salt tolerance of Populus euphratica at different developmental stages was evaluated and ranked using the fuzzy mathematical membership function. The results showed that: (1) The epidermal tissue of leaves became more developed with the developmental stages, while leaf thickness, palisade tissue, and spongy tissue showed a decreasing and then increasing trend. They were lowest at the mature stage, near-mature stage, respectively, and highest in the over-mature stage. The ratio of palisade to spongy was greater than 2.58 in each developmental stage, indicating good adaptability of Populus euphratica to saline stress across various developmental stages. (2) The salt tolerance of Populus euphratica at five different developmental stages was ranked from strong to weak as follows: over-mature > mature > seedling > near-mature > young. Leaf anatomical structure indicators can effectively reflect the salt tolerance characteristics of Populus euphratica and serve as an evaluation index for salt tolerance. Over-mature and mature stages exhibited stronger salt tolerance.





Effect of nitrogen addition on leaf chlorophyll and nutrient content of typical plant species in peatland of the Great Hing’an Mountains.

FENG Huanhuan, GAO Siqi, GAO Jinli, DU Yu, LIU Zhendi, CHEN Ning, SONG Yanyu

2025, 44(5):  1456-1464. 

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As the main pigment for plant photosynthesis, chlorophyll content is closely related to soil nitrogen availability, with consequence on plant growth and nutrient absorption. We conducted a long-term nitrogen addition experiment (N1: 6 g·m^-2·a^-1; N2: 12 g·m^-2·a^-1; N3: 24 g·m^-2·a^-1) in the permafrost region of the Great Hing’an Mountains to investigate the effects of nitrogen addition on plant growth and nutrient characteristics of peatland. The response patterns of leaf chlorophyll content and carbon, nitrogen, and phosphorus contents and their stoichiometric ratios to nitrogen addition were analyzed for typical peatland plants, including Betula fruticosa, Chamaedaphne calyculata, and Vaccinium uliginosum. The results showed that nitrogen addition increased leaf chlorophyll contents of B. fruticosa, C. calyculata, and V. uliginosum. Chlorophyll contents showed a trend of first increasing and then decreasing with increasing nitrogen addition levels. Mid-level of nitrogen addition significantly increased total leaf carbon contents of B. fruticosa and C. calyculata, but did not affect that of V. uliginosum. Nitrogen addition significantly increased total nitrogen contents of B. fruticosa and C. calyculata leaves, while simultaneously reduced the total phosphorus content and C/N ratio, and increased foliar N/P ratio of all the three species. Leaf chlorophyll contents of B. fruticosa, C. calyculata and V. uliginosum were significantly positively correlated with total leaf nitrogen content, whereas negatively correlated leaf C/N ratio. The chlorophyll content of C. calyculata was significantly positively correlated with C/P and N/P. In contrast, the chlorophyll content of V. uliginosum leaves was significantly positively correlated with total nitrogen, C/P, and N/P, and significantly negatively correlated with total phosphorus and C/N. Our results suggested that the growth of peatland plants was limited by nitrogen. Nitrogen addition can improve the photosynthetic capacity of peatland plants in permafrost regions, promote nitrogen absorption and accumulation, and change ecological stoichiometry.





Diversity and dominant species identification of indigenous arbuscular mycorrhizal fungi in the rhizosphere of ancient Ginkgo biloba in Shanghai.

MAO Jieying, LIU Wei, YANG Yaying, CHEN Baodong, SU Xiaona, ZOU Ziwei, TANG Yaohua

2025, 44(5):  1465-1473.  doi:10.13292/j.1000-4890.202505.034

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Ginkgo biloba is a unique relict tree species in China, whose root system can form a mutually beneficial mycorrhizal system with arbuscular mycorrhizal fungi (AM fungi). To determine the dominant indigenous AM fungi in the rhizosphere of ancient G. biloba in Shanghai, root and soil samples from ancient (about 200 years old) and adult G. biloba (about 50 years old) were collected. The infection characteristics of AM fungi in roots were determined by acetic acid ink staining with subsequent microscopic examination. The classification of genus and species and dominance analysis was carried out using morphological and molecular identification methods. The results showed that the structure of AM fungal community of roots were of intermediate type (Type I). The mycorrhizal infection rate of root system of ancient G. biloba (41.1%) was significantly lower than that of adult G. biloba (60.0%). Furthermore, 20 AM fungi species were isolated from the rhizosphere soil of ancient G. biloba, of which 8 genera and 13 species were identified morphologically. Through induced cultivation, four dominant species were obtained. Three out of the four species were molecularly identified as Claroideoglomus claroideum, Funneliformis mosseae, and Septoglomus viscosum. Our results provide a basis for promoting the application of locally dominant indigenous AM fungi of ancient G. biloba in environmental conservation, plant growth promotion and the rejuvenation of ancient trees.





Bacterial community characteristics of different shrub soils in a semi-arid area of northwest Shanxi.

FAN Qirui, HAO Jianhua, ZHANG Xiujuan, LI Dale, LI Junjian

2025, 44(5):  1474-1482.  doi:10.13292/j.1000-4890.202505.014

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We analyzed the composition, structure, and potential functions of soil bacterial communities in different shrubs in the semiarid region of northwest China, including Cotoneaster acutifolius, Lonicera japonica, and Cornus alba. The bacterial composition was measured with high-throughput sequencing of the 16S rRNA gene. The correlations between soil bacterial communities and soil physicochemical factors and extracellular enzyme activities were analysed using redundancy analysis and the Mantel test. The results showed that: (1) Soil physicochemical factors and enzyme activities varied significantly among the different shrub types (P<0.05). The Cotoneaster acutifolius soil exhibited the highest levels of total carbon, total nitrogen, nitrate, and available phosphorus. (2) Soil bacterial communities differed significantly among the three shrub types (P<0.01). The relative abundances of Actinobacteriota, Methylomirabilota, Proteobacteria, Firmicutes, Myxococcota and Gemmatimonadota differed significantly among the three shrub types (P<0.05). (3) The metabolic functions of bacterial communities predicted by the FAPROTAX database indicated the highest abundance of functional populations in Cotoneaster acutifolius soil. The analysis of co-occurrence network revealed a more complex linkage between bacterial phyla and functional populations in Cotoneaster acutifolius soil. (4) Redundancy analysis and Mantel test indicated that soil catalase activity, alkaline protease activity, and total nitrogen were the main factors influencing bacterial community structure in different shrub soils, playing a crucial role in driving bacterial community composition and structure. In summary, we found that soil fertility and bacterial community function level of Cotoneaster acutifolius were higher than the other vegetation types, suggesting that Cotoneaster acutifolius could be prioritized for vegetation restoration in the study area.





Growth dynamics and resource allocation strategy of Bromus tectorum L., an ephemeral in Junggar Desert.

YAN Jiayue, LI Qian, ZHANG Bo

2025, 44(5):  1483-1489.  doi:10.13292/j.1000-4890.202505.004

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Ephemeral plants are a unique group of flora in Xinjiang. Studies on growth and resource allocation are helpful in understanding their survival strategies. Bromus tectorum L. is a typical ephemeral plant in northern Xinjiang, playing an important role in the spring pasture restoration. In this study, we examined the phenological rhythm, growth dynamics, biomass allocation and reproductive output of B. tectorum distributed in Junggar Desert. Seedlings emerge in late fall, survive overwinters under snow, reach their maturity in late spring and die in early summer. In spring, B. tectorum grows rapidly and shows a fast development rhythm, which takes 52 days from tillering stage to maturity. With plant development, aboveground biomass increased rapidly, belowground biomass increased slowly, and root/shoot ratio decreased from 0.6 at tillering stage to 0.13 at fruit ripening stage. With the rapid decrease of root/shoot ratio, plants shifted from vegetative growth stage to reproductive growth stage. There is allometric relationship between reproductive biomass and vegetative biomass, and between belowground biomass and aboveground biomass. With increasing plant size, the reproductive output increased linearly, thereby reproductive allocation remained relatively stable (39%). The rapid growth-development rhythm and resource allocation strategy of B. tectorum in spring can achieve stable reproductive output of individual plants of all sizes, which has important ecological significance in maintaining population renewal and reproduction.





Effects of novel inhibitor application on maize yield and greenhouse gas emissions.

LI Yaqun, WANG Shuai, LIU Kai, ZHANG Kun, LI Dongwei, LI Jingyuan, WANG Wenyu, WANG Wei, LI Jie

2025, 44(5):  1490-1497.  doi:10.13292/j.1000-4890.202505.040

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Plant extract cyclopentanone (CCO) has dual effects in inhibiting urease activity and nitrification, with potential as an environmentally friendly and efficient novel inhibitor. In this study, a ¹⁵N labeled field microcosm experiment was conducted to investigate the effects of CCO application on maize yield and soil greenhouse gas (CO₂, CH₄, and N₂O) emissions. The sources of N₂O production were quantified and the abatement effects of CCO on N₂O emissions were evaluated. There were four treatments in the experiment: (1) blank control (CK); (2) urea treatment alone (U); (3) NBPT (N-(N-butyl)thiophosphorictriamide) and DMPP (3,4-dimethylpyrazole-phosphate) with urea (ND); and (4) CCO (2-cyclopenten-1-one) with urea (CCO). Each treatment was replicated for three times. The results showed that CCO had a greater potential to increase maize yield than NBPT and DMPP, with yield increasing by 77.3% and 12.7% compared to CK and the U treatment, respectively. CH₄ uptake under the CCO treatment was significantly increased compared to that under U treatment, with cumulative emission reductions of CO₂ and N₂O of 9.9% and 12.8%, as well as better emission reductions than that of ND. Combined global warming potential (GWP) and greenhouse gas emission intensity (GHGI) were reduced by 14.8% and 24.2%, respectively. N₂O derived from fertilizer nitrogen was reduced by 35.1%. In conclusion, CCO combined with urea can synergistically increase crop yields and reduce greenhouse gas emissions from farmland, while reduce the loss of fertilizer nitrogen in the form of N₂O.



Identification and phylogenetic analysis of Sichuan isolates of zucchini yellow mosaic virus from pumpkin.

CHEN Cheng, WANG Jian, FU Rongtao, CHEN Xiaojuan, LI Xingyue, CHEN Xuejuan, LU Daihua

2025, 44(5):  1498-1508.  doi:10.13292/j.1000-4890.202505.038

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To investigate whether pumpkins displaying mosaic symptoms harbor plant viruses, we conducted an analysis of pumpkin samples from Sichuan using the small-RNA deep sequencing technique. We analyzed a complete genome of the zucchini yellow mosaic virus (ZYMV), designated as the SCSN isolate. The SCSN isolate has a genome length of 9572 nt and encodes a 351.1 kDa polyprotein. Comparative sequence analysis revealed that the SCSN isolate shares the highest similarity (97.4% amino acid identity) with the WM isolated from Zhejiang. Recombination analysis indicated that the SCSN isolate originated from recombination events involving the WM isolate and the Ver isolate from Spain. A phylogenetic analysis, based on the SCSN whole genome sequence and 159 sequences from GenBank with a genome length exceeding 9300 nt, revealed clustering of ZYMV isolates from 28 countries and regions into seven distinct groups. Notably, the SCSN isolates formed a distinct cluster within the first group. There was a correlation between the phylogenetic evolution of ZYMV and its geographical distribution, highlighting the existence of dominant ZYMV taxa. As far as this knowledge, this is the first report of the complete genome of a ZYMV isolated from Sichuan, and would contribute to the development of strategies for preventing the spread of ZYMV through long-distance transmission.





Water ecological health assessment of Baoying Lake based on water quality and benthic macroinvertebrates.

YANG Shuyu, WANG Suhong, WU Yan, LEI Kaiwen, LI Mingjie, CAI Yongjiu, LIU Ling, ZHANG You

2025, 44(5):  1509-1517.  doi:10.13292/j.1000-4890.202505.036

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A comprehensive evaluation of water quality using both physicochemical and biological approaches is of great importance for water resource management and protection. In this study, we conducted monthly surveys of physicochemical properties and quarterly monitor of benthic macroinvertebrate of Baoying Lake, Yangzhou, Jiangsu Province, during August 2020 to July 2021. We analyzed the relationships between benthic macroinvertebrate community structure and environmental factors, and assessed the aquatic ecological health status of Baoying Lake using acomprehensive trophic level index, comprehensive water quality identification index, and comprehensive biological index based on the entropy weighting method. Results showed that Tanypus chinensis, Propsilocerus akamusi, Limnodrilus hoffmeisteri, Sinotaia purificata and Sinotaia aeruginosa were the dominant species among the 15 species of benthic macroinvertebrates. Chironomidae larvae and Gastropoda predominantly determined the spatiotemporal distribution of density and biomass of benthic macroinvertebrates, respectively. Physicochemical properties except water depth showed no significant spatial difference but strong seasonal variations. Specifically, transparency (SD) was higher in winter compared to other seasons, while permanganate index (COD_Mn) and total nitrogen (TN) were higher in summer than other seasons. SD, COD_Mn, and TN were the main environmental factors affecting the community structure and distribution of benthic macroinvertebrates. The annual nutrient level of Baoying Lake fell within the mesotrophic-moderately eutrophic range. Baoying Lake was at the Class III-IV as indicated by the comprehensive water quality identification index, and at a general to poor state as indicated by the comprehensive biological index. The results of the biological evaluation of water quality were slightly worse than that based on the physicochemical evaluation, indicating that water quality was not the only factor jeopardizing the ecological health of Baoying Lake.





The effects of feeding and short-term starvation on the thermal and hypoxia tolerance of Clarias gariepinus.

XIANG Ping, ZHANG Yongfei, HUANG Keren, FU Shijian

2025, 44(5):  1518-1524.  doi:10.13292/j.1000-4890.202505.002

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To investigate the effects of feeding and short-term starvation on the thermal and hypoxia tolerance of Clarias gariepinus, the critical temperature (CT_max and CT_min), lethal temperature (LT_max and LT_min), critical oxygen pressure (P_crit) and the loss of equilibrium (LOE) of experimental fish were measured at 25 ℃. The critical metabolic rate (MR_pcrit) and marginal metabolic rate (MR_LOE) were calculated. The results showed that both CT_max and LT_max decreased significantly, whereas both P_crit and MR_pcrit increased significantly after feeding (P<0.05). The CT_min, LT_min, LOE, and MR_LOE showed no variation between the feeding group and feeding control group. In addition, CT_max, LT_max and LT_min decreased significantly after starvation (P<0.05), while LOE was higher in starvation group than that in starvation control group (P<0.05). There was no significant difference in CT_min, P_crit, MR_pcrit, and MR_LOE between the starvation group and starvation control group. These results suggest that the heat and hypoxia tolerance of Clarias gariepinus were weakened by feeding digestion and short-term starvation stress, and that cold tolerance was enhanced after short-term starvation, which is related to the changes in metabolic rate and adjustments in some physiological functions of Clarias gariepinus during feeding digestion and starvation.





Monitoring activity rhythm and time allocation of common tern during breeding period using infrared cameras.

HAN Yuxin, LIU Bin, CHU Pengfei, QIAO Zhenglei, YUAN Baodong

2025, 44(5):  1525-1531.  doi:10.13292/j.1000-4890.202505.041

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We investigated the activity rhythms and time allocation patterns of common terns (Sterna hirundo) and analyzed their behavioral patterns during breeding season from April to July 2019 in Dafeng Elk National Nature Reserve, Jiangsu Province, China. Infrared cameras were used to record the behaviors during the nest-building period of common terns. Twenty infrared cameras were deployed for a total of 320 d, and 100 nests were recorded, 96 of which recorded common tern activities. The behavior of breeding common terns was dominated by nest-sitting and calling (43.8%±7.7% and 30.1%±7.2% of the total behavioral frequency, respectively), followed by defense (6.2%±2.6%). Other behaviors accounted for a relatively low percentage. Common terns spent 16% more time sitting on the nest at night than during the daytime and 33% less time calling at night than during the daytime. The proportion of nest-sitting behavior was significantly higher in the mid-breeding period than that in the pre-breeding and post-breeding periods (60.0%±3.3%, 30.8%±6.5%, and 40.6%±5.7%, respectively). Nest-sitting had a rhythmicity, with peaks during 12:00-14:00 and 22:00-24:00 and troughs during 06:00-08:00 and 14:00-16:00. In contrast, the other behaviors showed no rhythmicity. Begging was significantly positively correlated with brooding and calling (P<0.01). Feather-grooming was significantly positively correlated with nest-sitting (P<0.01). Foraging was significantly positively correlated with nesting (P<0.01). Brooding was significantly positively correlated with nesting and defending (P<0.05). Foraging was significantly positively correlated with feather-grooming and nest-sitting (P<0.05). No significant correlation was observed for other behaviors. This study provides basic data for the conservation and management of breeding common terns and for subsequent breeding ecological studies.





Benthic macroinvertebrate diversity and community pattern in Chaobai River Basin, Beijing.

HAN Jing, LUO Zunlan, SUN Guang, XIAO Nengwen, SHENG Xiangrui, SONG Zebang, KANG Lingling

2025, 44(5):  1532-1542.  doi:10.13292/j.1000-4890.202505.001

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To understand the diversity and spatial distribution of benthic macroinvertebrates in the Chaobai River Basin, surveys of macrobenthos in the main rivers were performed in summer (July) and autumn (September) of 2022. The community structure characteristics, diversity features, and niche of dominant species were analyzed. A total of 153 taxonomic units of macrobenthos were identified, with insects as the main dominant group. Baetis sp. and Hydropsyche sp. were the common dominant species in both seasons. The abundance of macrobenthos showed patterns from high to low as north > south, tributary > mainstem, upper-stream and middle-stream > lower-stream. The α-diversity of the benthic community showed no seasonal difference. However, the Shannon index and the richness index had significant geographical variations. The heterogeneity of macrobenthic communities was high among different seasons, and the pattern of β-diversity was dominated by turnover components. Baetis sp. and Hydropsyche sp. had the largest niche breadth in both seasons, occupying a wider resource utilization spectrum. The niche overlap between Polypedilum paraviceps and Tanytarsus chinyensis in summer, between Baetis sp. and Hydropsyche sp. in autumn was the highest, indicating intense interspecific competition. Our results suggested the mountain tributaries of Chaobai River Basin nurtured relatively high macrobenthos diversity, while the community structure of macrobenthos in the urban reaches was relatively single, forming a typical mountainous-urban macrobenthos spatial pattern. This study can provide data basis for related research in the Chaobai River Basin, and facilitate formulating ecological management and biodiversity conservation policies for urban rivers.





Seasonal and geographic distribution characteristics of mercury concentration in leaf litter of typical vegetation types.

HAN Shuyu, NIU Xiang, WANG Bing, WANG Zhangwei, ZHANG Xiaoshan, WANG Qiang, DU Jiajie, LIU Pingping

2025, 44(5):  1543-1550. 

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To clarify the seasonal and regional distribution of mercury (Hg) concentration in leaf litter of typical vegetations, we collected leaf litter of the main dominant tree species for Hg concentration analysis in representative areas with serious Hg pollution, including Guizhou, Jilin, Shaanxi, Hubei, Liaoning, and Chongqing, as well as at least two provinces in each of the seven geographic regions in China during August 2020 to October 2021. The results showed that: (1) Among the different vegetation types, Hg concentration in leaf litter of evergreen broad-leaved forests (75.88±22.28 ng·g^-1, ranging from 41.68 to 181.58 ng·g^-1) was 1.97 times as high as that of deciduous broad-leaved forests (38.58±30.65 ng·g^-1, ranging from 2.11 to 123.86 ng·g^-1). (2) In terms of seasonal pattern, leaf litter Hg concentration of most tree species increased gradually with the growing season. (3) On the spatial scale, leaf litter Hg concentration showed a trend of east China > central China > southwest China > south China > northwest China > northeast China > north China. Leaf litter Hg concentration in east China being 77.57±29.65 ng·g^-1 (ranging 38.04-109.01 ng·g^-1), which was 3.01 times higher than that in northeast China (25.73±8.28 ng·g^-1, ranging 11.95-37.01 ng·g^-1). In northeast China, central China and northwest China, leaf litter Hg concentration was higher in the heavily Hg-polluted sites than in the non-heavily polluted sites. Our results can be applied for the selection of afforestation species in Hg-polluted sites, and provide data support for assessing Hg absorption capacity of forest ecosystems.





Characteristics of mercury fraction of forest soil along an urbanization gradient in Shanghai.

LI Ran, WANG Yanlin, WANG Yongjie, DENG Hong

2025, 44(5):  1551-1560.  doi:10.13292/j.1000-4890.202505.032

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Urbanization and plant community play important roles in mercury migration and transformation in soils. To investigate the characteristics of mercury along an urbanization gradient, we analyzed the total mercury (THg), methylmercury (MeHg), and total organic carbon (TOC) concentrations in the soil of three forests, i.e. Cinnamomum camphora forest, Metasequoia glyptostroboides forest and evergreen-deciduous mixed forest, from the outer suburb, inner suburb and central urban district of Shanghai. The speciation of soil mercury was analyzed by thermal analysis method. The results showed that: (1) the THg concentration in the surface soil (0-2 cm) of urban forests varied from 34.01 to 317.98 ng·g^-1, with an obvious spatial pattern of central urban district > inner suburb > outer suburb, indicating that soil mercury was affected by urbanization. Based on the annual data, MeHg concentration of surface soil was correlated with THg concentration (R²=0.323, P<0.01) instead of soil TOC concentration (P>0.05). (2) Across the 0-20 cm soil profile, soil MeHg concentration was significantly positively correlated with both THg and TOC concentrations (R²_THg=0.231, R²_TOC=0.588, P<0.01). Hg forms affected the formation of mercury methylization. The speciations of adsorbed and organically bound mercury were important factors influencing the methylation of mercury in soil. (3) Compared to Cinnamomum camphora forest, soil MeHg concentration was higher in Metasequoia glyptostroboides forest and mixed forest, indicating that soils under deciduous trees were more methylated.




Effect of mercury stress on root growth and mercury accumulation in different color rice cultivars.

LIU Shuang, WANG Pengliang, ZHONG Shunqing

2025, 44(5):  1561-1568.  doi:10.13292/j.1000-4890.202505.028

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Mercury (Hg) contamination in rice and its resultant health risks to human have received considerable attention. It is urgent to find rice cultivars with low accumulation of Hg. By using hydroponic experiments, the responses of root morphology, activity, physiological characteristics of the three rice cultivars (black rice, red rice, and hybrid rice) were investigated under different levels of Hg stress (0, 0.5, 1.0 and 2.5 mg·L^-1). The accumulation and transportation of Hg within plants were studied as well. Our results showed that Hg concentration higher than 0.5 mg·L^-1 could significantly inhibit root growth, the longest root length and root volume of hybrid rice by 36.8%, 12.6% and 28.6%, respectively. Compared with the control, 0.5 mg·L^-1 Hg stress increased root activity of red rice and hybrid rice by 28.7% and 6.6%, respectively, while 1.0 and 2.5 mg·L^-1 Hg stress could decrease root activity of the three cultivars. Malondialdehyde (MDA) concentration in the three cultivars increased under Hg stress. With the increases of Hg concentration, the activities of peroxidase (POD) and catalase (CAT) in black rice and red rice increased first and then decreased, and reached the maximum value at 0.5 mg·L^-1. The CAT activity of hybrid rice reached the maximum value at 1 mg·L^-1 Hg concentration, which was 69.5% higher than that of control. The highest concentration of total Hg was observed in black rice roots under the 0.5 and 1.0 mg·L^-1 of Hg stress, and in the red rice root when exposed to 2.5 mg·L^-1 Hg stress. The translocation factors of Hg in red rice and black rice were lower than that of hybrid rice. Our results provide a theoretical basis for better understanding the resistance of colored rice to Hg toxicity and for selecting rice cultivars with low Hg accumulation.





Effects of cadmium and nickel stress on growth and physiological characteristics of Pennisetum americanum × Pennisetum purpureum and Festuca arundinacea seedlings.

GUAN Zheng, ZHANG Fenguo, LIANG Furong, ZHANG Sanqing, GUAN Zhengping, WANG Yongji

2025, 44(5):  1569-1580.  doi:10.13292/j.1000-4890.202505.011

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We investigated the adaptive characteristics and physiological mechanisms of Pennisetum americanum × P. purpureum and Festuca arundinacea under cadmium (Cd) and nickel (Ni) stresses. Seedling biomass and resistance physiological characteristics of those two species were measured under different concentrations of Cd and Ni. The results showed that the concentrations ranging from 0 to 50 mg·L^-1 of Cd promoted the fresh weight of P. americanum × P. purpureum shoot. At a concentration of 200 mg·L^-1, the seedling biomass of both species decreased significantly. The activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) initially increased and then declined with the increases of Cd concentration. Under Ni stress, the malondialdehyde (MDA) content and superoxide anion content of both species peaked at the concentration of 300 mg·L^-1. The soluble protein content of P. americanum × P. purpureum reached its maximum at the Ni concentration of 300 mg·L^-1, while Festuca arundinacea exhibited the highest soluble protein content at the concentration of 200 mg·L^-1. Principal component analysis and membership function evaluation were employed to analyze the morphological and physiological indices of those two species. The results indicated that P. americanum × P. purpureum exhibited the highest stress resistance under Cd stress, while Festuca arundinacea performed best under Ni stress. Overall, our results provide valuable insights into the potential use of those two species in the phytoremediation of Cd and Ni polluted soils.





Accumulation, tolerance, and photosynthetic response of cadmium in Eclipta prostrata.

SU Ya, WANG Haijuan, WANG Hongbin

2025, 44(5):  1581-1591.  doi:10.13292/j.1000-4890.202505.016

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To screen new cadmium (Cd)-accumulating plants, eight Asteraceae species were cultured in nutrient solution containing 10 mg·L^-1 Cd. Eclipta prostrata exhibited the strongest capacity of Cd accumulation. Consequently, the accumulation, tolerance and photosynthetic response of Cd in E. prostrata were further determined by pot experiment with different soil Cd concentrations (0, 5, 15, 35 and 50 mg·kg^-1). The results showed that higher Cd concentrations in the shoot (64.01 mg·kg^-1) and root (45.84 mg·kg^-1) of E. prostrata were detected when treated with 50 mg·kg^-1 Cd. Both the bioconcentration factor and translocation factor of Cd were higher than 1. The subcellular distribution of Cd concentration in the leaves was as follows: cell wall > soluble component > mitochondria and chloroplasts ≈ nucleus. Furthermore, plant height, chlorophyll b and total chlorophyll contents increased significantly under 5 mg·kg^-1 Cd treatment, but the aboveground biomass and photosynthetic pigment contents in leaves decreased significantly under the treatments of 35 and 50 mg·kg^-1 Cd. Further analysis revealed that 5-35 mg·kg^-1 Cd treatments induced a significant increase in the level of malondialdehyde (MDA) in the leaves. The stomatal conductance, transpiration rate, and the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) were significantly increased under 50 mg·kg^-1 Cd treatment in comparison to the control, but without significant difference in net photosynthetic rate. The results of stepwise regression analysis showed that shoot Cd concentration was positively correlated with leaf CAT activity but negatively correlated with leaf MDA content. In conclusion, although E. prostrata is not a Cd hyperaccumulator, it shows a strong capacity to accumulate and translocate Cd, which could be useful for phytoremediation of Cd-contaminated soils.





Effect and mechanism of modified iron nanocomposites on the removal of dechlorane plus.

DUAN Yunsi, ZHANG Hongling, DONG Wanling, CHEN Liangliang, SHI Yihui, MA Guofeng

2025, 44(5):  1592-1600.  doi:10.13292/j.1000-4890.202505.013

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Dechlorane plus (DP) is a class of widely used chlorinated flame retardants that are persistent, long-range migratory and bioaccumulative, posing serious harm to the ecological environment and human health. It has been included in the list of key new pollutants for control in China in 2023. Currently, most of the research on DP focuses on its environmental distribution and toxicity effects, but less on the related remediation techniques and mechanisms. In this study, biochar (BC) and rhamnolipid (RL) were used to modify nano zero-valent iron (nZVI) to obtain modified nZVI composites (RL/nZVI@BC), aiming to examine the removal effect of DP under different conditions and to investigate the removal mechanism of DP by this remediation material in combination with the change of morphology and structure properties of RL/nZVI@BC. The results showed that the modified nZVI composites enhanced DP removal from water. The removal rate of syn-DP and anti-DP in water by RL/nZVI@BC reached 98.4% and 97.6% under the conditions of nZVI:RL:BC=1:0.01:2, the material dosage of 2 g·L^-1, the DP initial concentration of 500 μg·L^-1, the pH of 3, the temperature of 45 ℃ and the concentration humic acid (HA) of 0 mg·L^-1. Kinetic analysis showed that the removal of DP by RL/nZVI@BC was consistent with pseudo-secondary degradation and adsorption kinetics (R² of 0.86-0.90 and 0.93-0.98, respectively), through the synergistic combination of π-π chemical bond binding adsorption of biochar, physical adsorption of specific surface energy, and reductive dechlorination of nZVI.





Spatial patterns of forest fire regimes and their influencing factors in China.

SHAO Xianzhuang, LI Chunlin, CHANG Yu, XIONG Zaiping, LIU Zhihua, CHEN Hongwei

2025, 44(5):  1601-1613.  doi:10.13292/j.1000-4890.202505.024

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Investigating the spatial patterns of forest fires could aid in better understanding the feedbacks between fire disturbance and forest ecosystems, providing a scientific basis for making rational decisions of forest fire management. In this study, we explored the spatial patterns of forest fire regimes in China using spatial point pattern analysis, cold and hot spot analysis and landscape spatial pattern analysis. We further analyzed the spatial nonstationarity of factors influencing the pattern of forest fire regimes in China using the global Poisson regression model (GPR) and geographically weighted Poisson regression model (GWPR). Our results showed that the interquartile range of the regression coefficients in the GWPR model was greater than twice the standard error of the GPR model, indicating spatial non-stationarity in the regression relationship between forest fire regimes and influencing factors. The GWPR model had a better fitting effect (deviance, AIC value, AICc value, percent deviance explained) than the GPR model, suggesting that considering spatial non-stationarity can improve model fitting. Road density and forest coverage were the main factors influencing the frequency of forest fires, while NDVI, road density and forest cover were the main factors influencing the size of burned patches. These influencing factors exhibited significant spatial non-stationarity, indicating that the dominant environmental factors for forest fire regimes in China were regionally specific. Our results could provide a scientific basis for making region-specific forest fire management decisions.





Thermal mitigation effect and optimization strategy of green space and water of residential compounds in central urban area: A case study of Xiamen Island.

HUANG Ning, LIU Qi, LAI Jianping, ZHANG Guoqin, LIAO Jiangfu, HUANG Yunfeng

2025, 44(5):  1614-1625.  doi:10.13292/j.1000-4890.202505.007

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Residential compound is a basic urban unit closely related to residents. It is of great significance to understand the thermal mitigation effects of green space and water in the residential compounds for improving the thermal environment of residential compounds. In this study, we took 12459 green space and water patches of 21 residential compounds in the central and western urban areas of Xiamen Island as research objects. Based on Landsat 8 remote sensing images in 2021 and green space and water vector data, the land surface temperatures were retrieved and the basic and spatial distribution characteristics of green space and water in residential compounds were analyzed. The thermal mitigation effects of green space and water in different types of residential compounds were analyzed and compared. The results showed that: (1) The average cooling range of green space and water in the studied residential compounds was about 50 m, and the average cooling amplitude was about 0.7 ℃. The cooling effect was more significant within 40 m, and the average proportion of cooling space covering the residential compounds was 72%. The average value of the thermal mitigation effect assessment (TMEA) index was 0.39. (2) The cooling range of green space and water in traditional residential compounds was larger than that in modern residential compounds, while the cooling amplitude of green space and water in the modern residential compounds was significantly larger than that in the traditional residential compounds. The average proportion of cooling space covering the residential compounds was larger than that in the traditional residential compounds. In general, the TEMA value of the modern residential compounds was higher than that of the traditional residential compounds. Among the modern residential compounds, the cooling range and amplitude of high-rise residential compounds were the largest, and the TEMA value was the highest, while those of high-rise and multi-storey mixed residential compounds were the smallest, and the value of TEMA was the lowest. The difference of land use layout in different residential compounds made different characteristics of the basic attributes and spatial distribution pattern of green space and water, resulting in the differences of thermal mitigation effect. (3) To enhance the thermal mitigation effect, we could increase the proportion of green space’s area and promote the synergistic effect of green space and water in the traditional residential compounds. For the mixed residential compounds, we could increase the proportion of green space and water’s area and the size of average patch area, improve the normalized vegetation index, and increase the connectivity of green space and water. Our results can enhance the understanding of the thermal mitigation effects of green space and water in residential compounds, and provide references for the optimization planning and practice of green space and water in various residential compounds with the aim of thermal mitigation in urban areas.





Dynamics of fractional vegetation coverage and vegetation spatial pattern in natural restoration process of rocky desertification in Yunnan Shilin Geopark.#br#

LI Kun, ZHANG Mengyuan, LI Yilun, XING Xiaoyi, FAN Shuxin, DONG Li

2025, 44(5):  1626-1635.  doi:10.13292/j.1000-4890.202505.030

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Vegetation restoration is crucial to prevent and control karst rocky desertification. Previous studies have extensively evaluated species changes in plant communities during vegetation restoration by field investigation. However, few studies have explored the spatial dynamics of vegetation. Such evaluation can reveal the interactions among vegetation patches, and better understand the process and mechanism of vegetation restoration. In this study, we explored the dynamics of fractional vegetation coverage and the spatial patterns by using 1.6 cm high-resolution remote sensing data from the unmanned aerial vehicle and field survey with a chronosequence approach in Yunnan Shilin Geopark. The results showed that in naturally restored vegetation, the total fractional vegetation coverage increased from 63.40% to 96.50% with succession, with the coverage of woody vegetation being increased from 4.29% to 96.50%. Furthermore, vegetation patches in the later succession stage was less fragmented, larger in mean patch size, and with simplified patch edges. Additionally, the global Moran’s I of vegetation increased first and then decreased, and peaked at the 10^th year of natural restoration, indicating strong aggregate of vegetation patches at this stage. These changes indicate that the restoration of large vegetation patches reduces the risk of karst ecosystem degradation to bare land. Overall, our results revealed the dynamics of fractional vegetation coverage and vegetation spatial pattern in natural succession, which could provide insights for ecological restoration practice in rocky desertification areas.





Responses of Crepidomanes latealatum distribution patterns to future climate change.

CEN Runlin, YE Tongxin, ZHANG Xianchun, ATSUSHI Ebihara, SHEN Yu, ZHANG Kaimei

2025, 44(5):  1636-1643.  doi:10.13292/j.1000-4890.202505.005

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Crepidomanes latealatum is sensitive to environmental changes. It is important to study the changes in the potential distribution areas of C. latealatum under climate change scenarios for the conservation of its wild resources. Using MaxEnt and ArcGIS software, we predicted changes in the spatial distribution pattern of C. latealatum in the potential distribution area of the world under different climate change scenarios (SSP126, SSP245, SSP370 and SSP585) in the current (1970-2000) and future (2021-2040, 2041-2060, 2061-2080, 2081-2100) based on 1276 geographical distribution data of C. latealatum, combined with 19 climatic factors. We further identified the main environmental variables affecting the distribution of C. latealatum. The MaxEnt model predicted the potential distribution areas of C. latealatum with high accuracy, with the AUC values of the training and testing sets being 0.962 and 0.966, respectively. The main environmental factors affecting its potential distribution were the warmest quarter, driest month precipitation, annual mean temperature, and temperature seasonality. C. latealatum is mainly distributed in 3°S-40°N, 95°E-140°E. The MaxEnt model predicted that under the current conditions, the suitable area of C. latealatum was mainly distributed in most parts of Asia, central and western Africa, and southeast Brazil, with a total suitable area of about 9.47×10⁶ km² and a highly suitable area of about 1.59×10⁶ km². Under the future climate scenario, the area of suitable areas in tropical East Asia and Africa will increase, while the area of suitable areas in temperate regions such as Europe and America will decrease. In addition, the area of suitable habitat for C. latealatum showed a general trend of first increasing and then decreasing over time under different climate scenarios. Under the background of global climate change, there are great challenges for the conservation of C. latealatum. Based on the current habitat of C. latealatum, protection zones should be established reasonably according to the local climate types, soil conditions, and other environmental factors, to ensure the adaptation of C. latealatum.





Prediction of potential suitable distribution area for pecan in Jiangxi based on MaxEnt model.

LI Chunhui, WANG Jianjun, CAI Zhe, YANG Aiping

2025, 44(5):  1644-1652.  doi:10.13292/j.1000-4890.202505.022

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To provide theoretical basis for the introduction and development of pecan (Carya illinoinensis (Wangenh.) K. Koch) in Jiangxi Province, based on North American distribution data, environmental and climate data, and terrain data, the maximum entropy (MaxEnt) model was used to simulate the suitable distribution areas of pecan in Jiangxi Province under the current climatic conditions and to predict changes under three climate scenarios using 167 effective distribution points and 11 environmental factors. The dominant environmental factors affecting the distribution of pecan in Jiangxi Province were analyzed. Results showed that the MaxEnt model had a high accuracy in predicting the suitable distribution areas of pecan, with the AUC value above 0.989. The suitable distribution areas were mainly affected by precipitation and temperature, with the precipitation of driest month (bio14), the mean temperature of warmest quarter (bio10), temperature seasonality (bio4), mean diurnal range (bio2), and the precipitation of wettest month (bio13) being the dominant ones. When the precipitation of driest month was 30-520 mm, the mean temperature of warmest quarter was 25-46 ℃, the temperature seasonality was 750-2600, the mean diurnal range was 10.4-21.9 ℃, and the precipitation of wettest month was 90-195 mm, they were beneficial for the growth of pecan. Under the current climatic conditions, most areas in Jiangxi Province are suitable for the growth of pecan. The potential highly suitable distribution areas and the potential suitable distribution areas accounted for 4.4% and 69.4% of the total area of Jiangxi Province, respectively. The suitable distribution areas were mainly distributed in hills, plains, and basins below an altitude of 500 m. Under the three climatic conditions, most areas of Jiangxi Province will still be suitable for growth of pecan, and the total suitable distribution areas will expand. Under the same climate scenario in the future, as time increases, the non-suitable areas will increase. As carbon emissions increase, potential highly suitable areas would move towards the western and southern regions of Jiangxi Province. Therefore, pecans have a wide range of adaptability, with the potential for introduction, cultivation, and promotion in Jiangxi Province.





Temporal and spatial distribution of climate suitable areas of ratoon rice in Sichuan Basin over the recent 50 years.

GUO Xiang, HU Rong, LI Xuyi

2025, 44(5):  1653-1661.  doi:10.13292/j.1000-4890.202505.015

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We investigated the temporal and spatial variations of climate suitable areas of ratoon rice in Sichuan Basin during 1971 to 2020, aiming to provide a theoretical reference for rice production and coping with climate change in Sichuan. According to the cropping system, the Sichuan Basin could be divided into five rice-planting areas. Based on the daily meteorological data of 106 weather stations from 1971 to 2020, the active accumulated temperature and the duration of safe growing season for ratoon rice were calculated. Subsequently, the Sichuan Basin was divided into climate unsuitable area, climate sub-suitable area, and climate suitable area. Finally, we analyzed the climatic resources and change trend of the five rice-planting areas, as well as the distribution characteristics and evolution trends of the ratoon rice climate suitable areas. The results showed that the safe growing season of ratoon rice in the Sichuan Basin displayed a prolonged trend over the recent 50 years. The active accumulated temperature of safe growing season also increased, with the extension of growing season and the increase of active accumulated temperature being the largest in the agricultural area of the western basin plain. If the latitude shifts northward by 1°, the duration of safe growing season will shorten by 2-7 d and the active accumulated temperature of safe growing season will decrease by 73-170 ℃·d. With an increase of 100 m in altitude, the duration of safe growing season will shorten by 2-6 d and the active accumulated temperature of safe growing season will decrease by 105-187 ℃·d. In summary, the ranges of climate suitable and sub-suitable areas of ratoon rice showed expansion trends in Sichuan Basin, which are manifested in the expansion from south to north and from east to west. Reasonable adjustment of planting system and selection of suitable cultivars are the main measures to improve the utilization rate of climatic resources in rice growing season and enhance the yield and quality of rice in the five rice-planting areas.





Optimization of NO₂ air monitoring stations based on spatial simulated annealing algorithm: A case study of the southwest Fujian urban agglomeration.#br#

#br#

QIU Yue, ZHU Pengfei, SU Ying, Abiot Molla, REN Yin

2025, 44(5):  1662-1670.  doi:10.13292/j.1000-4890.202505.039

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Air quality evaluation is a crucial component of urban planning and control, closely related to human health and society development. The rational deployment of air quality monitoring stations is vital for predicting the spatial variations of air quality. This study aimed to evaluate the minimum sample size of air monitoring points to represent the optimal prediction accuracy of air NO₂ and to establish reliable inputs for predictive models. We designed a methodological framework for spatial optimization of air quality monitoring networks based on spatial simulated annealing algorithm, with the ground-level NO₂ monitoring stations in the southwest Fujian of China as an example. The layout of monitoring stations was improved based on the spatial simulated annealing algorithm with the minimum Kriging variance, enhancing the precision and effectiveness of air pollution monitoring. During the optimization process, a perturbation algorithm was used to change the layout of monitoring stations. The minimum Kriging variance (MKV) was employed for evaluation (without considering the total financial budget limit), seeking the highest optimization efficiency in sampling quantity. By optimizing the spatial layout of ground-level NO₂ air pollution monitoring stations, we found that after adding 160 monitoring stations, the MKV of NO₂ decreased from 0.09 μg·m^-3 to 0.02 μg·m^-3, and the prediction accuracy was increased by 71.46%. This optimization is likely to improve the coverage and sampling density of the monitoring system, enhancing the accuracy and reliability of monitoring data. This is crucial for timely identification and response to pollution sources, monitoring air quality trends, and formulating environmental policies. Moreover, this method could potentially be applied to monitor other forms of pollution (water, soil, and noise). This study provides a reference for the future optimization of air monitoring station deployment and management.





Research progress of salt-affected land in Songnen Plain.

ZHOU Daowei, HU Juan, LI Qiang, HUANG Yingxin

2025, 44(5):  1671-1677.  doi:10.13292/j.1000-4890.202505.006

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To promote the improvement and utilization of salt-affected land in Songnen Plain, northeast China, we summarized the research results of salt-affected land in Songnen Plain, sorted out techniques of the improvement and utilization, and put forward several questions needed further research. The salt-affected land in the Songnen Plain was formed 10000 years ago, and its development was intensified in the past 1000 years. Water flushing and washing is a feasible and effective technique for improving the salt-affected land to develop paddy field. Sand mulching near the salt-affected land and straw mixing are most possible measures to improve salt-affected land for dryland. A cost-benefit model for improving salt-affected land was established, and an improvement strategy focusing on the forming causes of the salt-affected land was proposed. Towards improvement and utilization, the salt-affected land classification and grading, and restriction of ions to crop production need to be further studied.





Research progress on the estimation of vegetation carbon storage of grasslands in China.

ZHAO Jiajun, HOU Peng, CHEN Yan

2025, 44(5):  1678-1687.  doi:10.13292/j.1000-4890.202505.044

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Grassland, as a critical terrestrial carbon reservoir in China, plays a crucial role in climate regulation and achieving the goals of carbon peak and neutrality. Based on relevant literature, we provided a comprehensive overview of representative estimation methods of grassland vegetation carbon storage and analyzed the sources of disparities in different estimation results. The results showed that since the beginning of the 21st century, there has been a significant variation in the estimated carbon storage values of grassland vegetation in China. The estimated carbon storage ranges from 0.56 to 4.66 Pg, with an average of 2.22 Pg. The estimated carbon density ranges from 216 to 1148 g C·m^-2, with an average of 654.23 g C·m^-2. The contribution of litter carbon storage fluctuates between 0.1% and 8.6%, with an average of 5.6%. Neglecting litter would underestimate total carbon storage. The global unit carbon density estimation method showed significant differences with other estimation methods (P<0.05). Carbon concentration in the aboveground, belowground and litter components is approximately 39.3%, 36.6%, and 30.7%, respectively. There were significant differences between the carbon concentration of aboveground vegetation and litter (P<0.05). Using the common carbon conversion factor of 45% could overestimate grassland vegetation carbon storage. Root/shoot ratios varied across different grassland types, ranging from 0.76 to 41.80, with a mean of 9.16. In summary, differences in estimation methods, data sources, and key parameters resulted in variations in the estimates of grassland vegetation carbon storage in China.





Research progress and prospects of ecological space identification technology in China.

GU Pengcheng, XU Chang, TIAN Zhiqiang, PENG Wenlong, LYU Xiao

2025, 44(5):  1688-1698.  doi:10.13292/j.1000-4890.202505.012

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Scientific identification of ecological space is the basis for promoting the modernization of land space governance system and governance capacity. We used literature review, inductive summarization and comparative analysis to clarify the concept of ecological space identification. We reviewed recent technological advancements and further defined the innovative pathways and directions for future research. China’s ecological space identification techniques primarily consisted of multisource data overlay analysis, ecological space evaluation, integration of the InVEST model with related spatial analysis methods, habitat identification for endangered species or nature reserves, and dynamic ecological space identification, with steady progress in their development and refinement. These techniques varied in scale, data requirements, research paradigms, and objectives, each possessing distinct advantages and limitations. Accordingly, we delineated the technical approaches with complete flow scheme for identifying ecological protection gaps by comprehensively applying various ecological space identification systems at multiple scales, complementing each other. Future research should focus on three key aspects: developing a comprehensive and multidimensional ecological space identification technology tailored to local conditions, fostering technological integration and interdisciplinary collaboration, and enhancing international cooperation and localized innovation.





Research progress of environmental behaviors and ecotoxicity of molybdenum disulfide nanomaterials.

ZHANG Yu, ZHAO Chenxu, JIN Caixia, ZHANG Xingli, ZHANG Guoqing, ZOU Wei

2025, 44(5):  1699-1710.  doi:10.13292/j.1000-4890.202505.042

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As one of the most concerned transitional metal dichalcogenides nanomaterials, molybdenum disulfide (MoS₂) has been widely applied in various fields due to its unique physical, chemical and biological properties. During the production, use, and disposal, MoS₂ nanomaterials inevitably enter the environment through multiple pathways. The potential threat of MoS₂ nanomaterials to ecosystems cannot be ignored. We summarized the research progress regarding the migration and transformation behaviors of MoS₂ after releasing into aquatic environments, and discussed the effects and mechanisms of environmental factors. We reviewed the toxicity effects and associated mechanisms of MoS₂ nanomaterials on plants, animals, and microorganisms, and elucidated the relationships between the ecotoxicity and physicochemical characteristics of MoS₂ (e.g., size, morphology, crystal structure, and element doping). We proposed the outlook regarding the research of environmental behaviors and ecotoxicity of MoS₂ nanomaterials, aiming to provide guidance for the research and application of nanomaterials in the same type in ecology and environment field.



Research progress on the regulation mechanism of organic acid content by non-Saccharomyces cerevisiae yeast.

SUN Wenjing, LI Ying, YANG Hui, SU Li, ZHANG Xue, CHEN Jiansheng, ZHANG Junxiang

2025, 44(5):  1711-1721.  doi:10.13292/j.1000-4890.202505.037

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Non-Saccharomyces cerevisiae, with the unique physiological and biochemical metabolic pathways, exhibits the potential to regulate the production and types of organic acids in wine. We systematically summarized non-Saccharomyces cerevisiae species with acid regulating ability, clarified the mechanisms in organic acid metabolism, and analyzed their applications in wine making. Through a comprehensive understanding of the characteristics and metabolic pathways of these non-Saccharomyces cerevisiae yeasts, we aimed to provide in-depth and systematic references for the application of non-Saccharomyces cerevisiae yeasts in regulating wine acidity.





Application of deep learning algorithms in identification and recognition of terrestrial arthropods.

ZHUANG Xiaohao, ZHANG Weixin, LIU Shengjie

2025, 44(5):  1722-1730.  doi:10.13292/j.1000-4890.202505.031

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Terrestrial arthropods are the most diverse animal taxa and play critical roles in human society and natural ecosystems. However, the taxonomic identification of terrestrial arthropods is a great challenge for diversity survey. With the development of computer vision technology, deep learning image recognition technology has shown a great potential for animal and plant recognition and classification and has increasingly become a new method for animal classification. Compared with plants and vertebrates, terrestrial arthropods were less explored the deep learning algorithm technology for the identification. Based on the diversity and ecological functions of terrestrial arthropods, we systematically introduce the principles, basic types and factors affecting the recognition accuracy of deep learning image recognition technology. Furthermore, we summarized the application cases and problems of deep learning recognition technology in the identification of soil arthropods. We prospected future research priorities in arthropod identification using deep learning, which outlines a milestone for achieving rapid, accurate and optimized identification of terrestrial arthropods, especially soil arthropods.





Application of radon as a tracer in water science research.

QIAN Chang, YU Jieyu, WANG Qianqian, LIU Yixuan, CHEN Yifan, LU Taotao, YU Zhiguo

2025, 44(5):  1731-1740.  doi:10.13292/j.1000-4890.202505.043

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Radon isotope (²²²Rn) is a natural radioactive gas, colorless and odorless, with a short halflife (t_1/2=3.8 days) and conservative chemical properties. Its concentration is higher in groundwater than in surface water. It is sensitive to sudden changes in subsurface geologic conditions, and thus can be used as a desirable tracer in water science research. However, the application of radon tracer technology in the field of water science is still in the primary stage. This review introduces the physical and chemical properties, detection and quantification methods of ²²²Rn. We evaluate the application of ²²²Rn as a tracer in quantifying the interactions between groundwater and surface water, as well as in the research of hydrogeochemistry, water environment monitoring, and hydrogeological exploration. The problems and deficiencies in the application of radon tracers are discussed. The broad prospects for their application in hydrogeochemistry, the mechanism of earthairmatter interaction processes, and water environment monitoring are elucidated. Suggestions are made for the future development of research in this field.





Progress in the application of the plasma technology to harmlessness and recycling utilization of urban solid waste.

CHENG Siwen, ZHOU Qixing, PENG Ting, LIU Fude

2025, 44(5):  1741-1752.  doi:10.13292/j.1000-4890.202505.035

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The plasma technology develops rapidly and has become a new research hotspot in recent years, with a wide range of applications. It has been applied to the urban solid waste treatment, but the full and unified application system has not yet been formed. We first briefly introduced the plasma technology and its classification. Then, we summarized its application to the harmlessness and resource utilization of urban solid waste (including plasma technology assisted biomass hydrogen production, catalytic CO₂ fuel generation, recycling metals in waste, surface modification of materials, recycling of radioactive waste and waste rubber, tires, glass, fibers, plastics, etc.), which was compared with traditional urban solid waste treatment methods. We analyzed their outcomes, aiming to provide the reference for the further improvement of this technology. Finally, the future research focus and the problems needed to face in the future (high cost, high energy consumption, difficult to large-scale application, etc.) are briefly discussed. In conclusion, in order to solve the increasingly serious problems of urban solid waste pollution, the plasma technology is applied to urban solid waste treatment and disposal, from the perspective of urban solid waste harmlessness and resources reuse, which can alleviate or even solve the current situation of urban solid waste pollution and achieve the goal of resources recycling.





Screening method of contaminated site remediation technologies based on case data mining.

WU Zhijun, TIAN Yuan, YANG Huan, GU Qingbao, XU Duanping

2025, 44(5):  1753-1760.  doi:10.13292/j.1000-4890.202505.033

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The screening of remediation technologies is a crucial process for efficiently repairing contaminated sites and improving land reuse. Currently, the screening index system for site remediation technology is too complex, and the weights of indicators rely on expert judgment. To overcome these challenges, we examine site characteristics and the implementation effects of remediation technologies with 514 Chinese cases from 2010 to 2022. A screening index system was established. The cases were divided into groups according to the remediation technology applied, and the most similar case to the specific site within each technical group was selected by the K-nearest neighbor method (KNN). This allowed for a comparison of implementation effects to quantify the indices associated with each technology. The entropy-TOPSIS method was then applied to evaluate the effectiveness of different remediation technologies. Taking a retired non-ferrous metal smelter site in Northeast China as an example, the most suitable remediation technology that aligned with its actual application was successfully selected. In conclusion, this method demonstrates high practicality and feasibility, which would be helpful for environmental protection workers and enterprises in China.